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Message-ID: <7104a73705060306553672f56a@mail.gmail.com>
Date: Fri, 3 Jun 2005 16:55:51 +0300
From: Volkan YAZICI <volkan.yazici@gmail.com>
Reply-To: Volkan YAZICI <volkan.yazici@gmail.com>
To: Terry Lee Tucker <terry@esc1.com>
Subject: Re: libpq, blocking/nonblocking mechanism
Cc: PostgreSQL Interfaces <pgsql-interfaces@postgresql.org>
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Hi,

On 6/1/05, Terry Lee Tucker <terry@esc1.com> wrote:
> PQsetnonblocking() causes PQsendQuery to send an sql string to the backen=
d
> and it returns immediately if you have set nonblocking to true. If you ha=
ve
> not set nonblocking to true, then PQsendQuery behaves just like PQexec; i=
t
> blocks, i.e., it waits for the query, update, delete, or whatever to comp=
lete
> before it returns program control back to your program. We set nonblockin=
g to
> True in our application and when the user queries a large table that coul=
d
> return thousands of records, we use PQsendQuery instead of PQexec; howeve=
r,
> if you do that, then you have to use PQconsumeInput and PQisBusy in
> conjunction with a select statement to monitor the backend connection soc=
ket
> so you can process the results when the query finishes. Another reason fo=
r
> using asynchronous queries is that you can provide a mechanism for the us=
er
> to cancel the operation.

Thanks so much for the explanation.

> Our application is X-Windows based written in C.
> All my examples are C. If you want to see any of it, you can let me know.

I'd be so appreciated to see them.

Regards.